1) To examine in more detail changes in the electrolyte composition and water content of lenses during formation and reversal of galactose cataracts. It is proposed, further, to correlate the alterations in ionic composition with those in bioelectric potential of these lenses which have now been successfully measured in rat lenses, for the first time, in an attempt to determine the mechanisms involved in cataract formation. 2) To initiate an investigation of oxidative metabolism of pigment epithelial cells as it relates to ion transport and bioelectric potential employing oxygen electrodes. 3) To complete the analysis of anion composition of the lens with the object of establishing the fixed charge on the lens protein in an effort to establish the magnitude of the Donnan effect and its possible importance on lens hydration. 4) To investigate further the role of the pigment epithelium in anion transport in relation to maintenance of intraocular pressure, employing explants of freshly removed retinal tissue from rabbit lenses. BIBLIOGRAPHIC REFERENCE: Kinsey, V.E. and McLean, I.W.: Studies on the crystalline lens XXI. Bidirectional carrier-mediated transport of lithium. Invest. Ophthal. 13:784-794 (1974).